1. Field of the Invention
The present invention relates to a press with a preferably vertically arranged high pressure chamber having a high pressure cylinder, end closures projecting into this cylinder and a press stand to take up the axial forces exerted on the end closures by a medium under high pressure. Presses of the type mentioned are used, among other things, for isostatic compression of powder bodies, resistance elements, and the like at pressures in the region of 1,000 -- 10,000 bar. The cylinder is charged outside the press stand with components to be treated, and then inserted in the press stand and supplied with pressure medium. The press stand is then removed after treatment and the cylinder is emptied outside the press stand.
2. The Prior Art
With presses of this type, the high pressure chamber with the closures completely inserted must have a shorter length than the clear opening of the press so that the clearance necessary for insertion and withdrawal of the chamber is obtained between the end closures and the press. When the pressure in the chamber is increased, the end closures are first forced out until they come into contact with support surfaces in the press stand and then move only as far as the support surface yields under the load. Because of the friction between the closures and the cylinder, the pressure chamber is still held between the support surfaces of the press stand with a considerable force even when the pressure is removed. This complicates removal of the pressure chamber. The end closures must therefore be returned to their innermost positions in the cylinder so that the clearance between the end closures and the support surfaces which is suitable for moving the press is again obtained. A press with appliances for achieving this insertion of end closures is described in U.S. Pat. No. 3,550,199.
In the known press, a piston was built into the end closure or the support of a press stand. The cross-section, taking up the load, in the end closure just below the pressure chamber space was thus reduced, as well as the load-transmitting contact surface of the end closure and the press stand. At relatively low compression pressure, this involves little or no inconvenience. At very high working pressures, for example at working pressures of more than 4000 bar, this involves a considerable inconvenience from the point of view of strength. Similarly, the suspension of a supporting ring for the end closure by means of spring units involves no problems when the diameter of the pressure cylinder is small, but a considerable problem when the diameter of the cylinder is large. There are certain problems in accommodating sufficiently strong or sufficiently many spring units. The new operating mechanism means a simplification which makes the manufacture simpler and less expensive, and which makes it possible to use simpler constructional material.